Adjustment of decay rates of organic matter in a latossolo vermelho-amarelo in the Araripe National Forest, Brazil

Abstract

The use of mathematical models is an alternative way to understand how management practices affect soil organic matter (SOM) dynamics because such models yield results on time scales that would be impossible to observe in field studies. The aim of this study was to parameterise and calibrate the application Century 4.0 in terms of the edaphoclimatic conditions of a Latossolo Vermelho-Amarelo of the Araripe Plateau and simulate the soil C dynamics in each compartment. The study was conducted in the Araripe National Forest (Floresta Nacional do Araripe ― FLONA). The soils are classified as Latossolos Vermelho-Amarelos with a medium clayey texture and a clay fraction consisting of kaolinite with iron and aluminium oxides. The physical and chemical properties of the soils were obtained at a depth of 0.00-0.20 m in 2012 and 2013. The best total organic carbon (TOC) result was an error of only 3% between the measured and simulated values, which was obtained with a PRDX (4) adjustment of 140 g m-2 C. After correcting for the C decay rate in the passive (PC), slow (SC) and active compartments (AC), absolute errors lower than 10% were obtained for the C values. The abiotic correction factors specific to each compartment were 0.89 for the active and passive compartments and 1.12 for the slow compartment. The sensitivity analysis indicates that all compartments are sensitive to variations in maximum and minimum temperature and that the clay content affects the TOC and the passive compartment.